Breast Positron Emission Tomography (PET) with 18F-FDG (2-deoxy-2-(18F)fluoro-D-glucose) was mainly used for staging and monitoring of treatment response of NAC, with the reduction of FDG uptake (P<0.001) was more evident than that of tumor size (P=0.005). However, FDG PET displayed a limited role in evaluation of primary breast cancer, brain and axillary lymph nodes metastases. There were publications regarding combined FDG PET/CT and breast MRI for breast cancer diagnosis and monitoring NAC response. The SUV on static PET and MRI findings were correlated well with molecular marker status of breast cancer (ER, PR, HER2), and were associated with clinical outcome. The change of choline integral on MRS was well correlated to the peak of SUV during NAC (r=0.84,P=0.02).The changes of dynamic PET parameters including rate constants for uptake, washout and FDG influx were moderately correlated with the DCE MRI parameters and can reflect the response status of NAC. However, PET/CT and MRI were performed by two machines at different time, so breast positioning is different, causing the lesion targeting sometimes difficult. Moreover, the selection of ROI/VOI for PET and MRS, DCE MRI is subjective with inter-observer bias. A new technology- PET/MR- can solve these problems. PET/MR has less radiation and offers more soft tissue details than PET/CT. A most recent PET/MR design- integrated PET/MR- is commercially available. Using the integrated PET/MR, patients can undergo whole body PET and MRI at the same time, followed by dedicated protocol for specific organ of primary tumor origin. The ROI/VOI of breast DCE MRI, MRS can be selected according to SUVmax site from PET, which is more objective and can ensure that the VOI/ROI is at same location across all techniques. PET/MR showed comparable reliability to PET/CT for detection of oncologic diseases, and contributed even more changes of clinical management than PET/CT. However, use of PET/MR for breast cancer was seldom reported.